In accordance with a rapid spread of information relevant apparatuses and communication apparatuses such as a personal computer, a video camera and a portable telephone in recent years, the development of a battery to be utilized as a power source thereof has been emphasized. The development of a high-output and high-capacity battery for an electric automobile or a hybrid automobile has been advanced also in the automobile industry. A lithium battery has been presently noticed from the viewpoint of a high energy density among various kinds of batteries.
Here, organic liquid electrolyte using a flammable organic solvent is used for a conventionally commercialized lithium battery, so that the installation of a safety device for restraining temperature rise during a short circuit and the improvement in structure and material for preventing the short circuit are necessary therefor. On the contrary, a solid state battery such that the liquid electrolyte is replaced with a solid electrolyte is conceived to intend the simplification of the safety device and be excellent in production cost and productivity for the reason that the flammable organic solvent is not used in the battery.
In the field of such a solid state battery, an attempt to intend the performance improvement of the battery is offered while noticing an interface between an active material and an electrolyte material. For example, in Patent Literature 1, an electrode body (a cathode layer) containing a cathode active material coated with lithium niobate and a solid electrolyte including a sulfide is disclosed. In addition, in Patent Literature 1, it is disclosed that an electrode body may contain a conductive agent such as acetylene black and Ketjen Black.